Urticaria, also known as hives, is a common skin condition that affects 1 in 5 people at some point in their lives. It causes intensely itchy, raised patches on the skin called weals, which can be round or ring-shaped and may merge together. These often appear after scratching and can affect any part of the body.

The condition is triggered when histamine and other chemicals are released into the bloodstream by mast cells. This causes fluid to leak from capillaries, leading to the raised welts on the skin. While the hives usually fade within 24 hours, the underlying condition can persist longer.

Urticaria is often accompanied by angio-oedema, which is swelling under the skin that typically affects softer areas like the lips, eyelids, or inside the mouth. Unlike hives, this swelling is more painful and can last longer. If angio-oedema occurs without hives, it may indicate hereditary angio-oedema, a different condition that requires specific testing and treatment.

Urticaria is classified into three types based on duration and cause:

Acute Urticaria: Lasts less than six weeks and is usually triggered by a known cause.
Chronic Urticaria: Lasts over six weeks, often with no identifiable trigger.
Physical Urticaria: Triggered by external factors such as scratching, cold, pressure, sunlight, or heat.
Common triggers include allergic reactions, infections, and emotional stress.

Although many hives resolve on their own, persistent or severe cases may require antihistamines, steroid tablets, or menthol creams to relieve itching.